The present invention relates to a touch panel input device, and in particular, to a touch panel input device which is disposed in a display section including a liquid-crystal device (LCD) and in which a coordinate signal is sensed using a change in a position depressed by a finger (fingertip), a pen or the same in association with a content displayed on the display section and the coordinate signal thus sensed is inputted to a device connected to the touch panel input device.
A touch panel input devices of prior art include a touch panel of transparent resistive film type. FIG. 1 shows in a cross-sectional view a configuration of the touch panel using transparent resistive films 500 of the prior art.
The touch panel 500 shown in FIG. 1 includes a transparent film 51, a first transparent resist film 52, a second transparent resistive film 53, a glass substrate 54, and a dot spacers 55 disposed over an upper surface of the second transparent resistive film 53 with a fixed gap therebetween.
The transparent film 51 includes a flexible transparent film member constituting a surface section of the touch panel 500. The film 51 includes, for example, a transparent plastic film such as polyethylene terephthalate (PET). The film 51 has a flexibility enough to easily bend or to easily change its form when depressed by a finger or a pen.
The first transparent resistive film 52 includes a transparent conductive film made of, for example, indium tin oxide (ITO) or SnO2. The film 52 is arranged entirely on a lower surface of the transparent film 51 and has nearly a uniform thickness. When the film 51 is pushed by a finger, the film 52 is distorted together with the film 51.
The second transparent resistive film 53 includes, like the first transparent resistive film 52, a transparent conductive film made of the above-mentioned same materials. The film 53 is arranged throughout on an upper surface of the glass substrate 54, which will be described later, and has nearly a uniform thickness.
The glass substrate 54 forms a bottom section of the touch panel. The film 53 having a uniform thickness is disposed entirely on an upper surface of the glass substrate 54.
The dot spacers 55 prevent the first transparent resistive film 52 on the transparent film 51 from being brought into contact with the second transparent resistive film 53 arranged on the glass substrate 54 in an no-input state of the panel 500. Additionally, density of dot spacers 55 determines magnitude of pressure required to bring the transparent resistive film 52 into contact with the transparent resistive film 53.
FIG. 2 shows in a cross-sectional view a state of the touch panel 500 using transparent resistive films of the prior art in which the panel is depressed by a touch panel pen or a fingertip of a user.
When the user pushes, by his or her finger or a pen, the transparent film 51 on the upper surface side of the touch panel 500, the films 51 an 52 are rendered to a distorted state as shown in FIG. 2.
The film 51 on the upper surface side of the touch panel 500 is bent by pressure of the pen or a fingertip, and the first transparent resistive film 52 makes contact with the second transparent resistive film 53. The films 52 and 53 are set to an electrically conductive state. By sensing the conductive state, the panel 500 detects an event of depression on the film 51.
FIG. 3 shows constitution of a sensor circuit to sense an input coordinate position in a touch panel using transparent resistive films of the prior art. The position sensor senses a pair of coordinates (input coordinates) of a contact point between the films 52 and 53.
The input coordinate sensor of the touch panel shown in FIG. 3 includes a first transparent resistive film 601, a second transparent resistive film 602, a first resistor 603 schematically shown on the first film 601, a second resistor 604 schematically shown on the second film 602, analog switches 605 to 608, and analog-to-digital (A/D) converters 609 and 610.
Although each of the resistors 603 and 604 includes one resistor having an ordinary contour in FIG. 3, the resistor actually has a planar shape, namely, a transparent resistive film like the first and second transparent resistive films 601.
The first resistor 603 (first transparent resistive film 601) has two electrodes respectively connected to the analog switches 605 and 606. The switches 605 and 606 are coupled with a power source voltage V and ground, respectively.
The second resistor 604 (second transparent resistive film 602) includes two electrodes linked with the analog switches 607 and 608, respectively. Connected to the switches 607 and 608 are a power source voltage V and ground, respectively.
In FIG. 3, the first and second transparent resistive films 601 and 602 are fixed or laminated onto each other such that the electrodes 605 and 606 of the film 601 are vertical to the electrodes 607 and 608 of the film 602. The first and second electrodes 603 and 604 are respectively coupled with the A/D converters 609 and 610.
Referring to the input coordinate sensing circuit shown in FIG. 3, description will a given of operation to sense a contact point, namely, a pair of coordinates associated with actual depression on the touch panel. Assume tat the transparent film 51 of the touch panel 500 is depressed at a position by a fingertip or a pen of the user, for example, as shown in FIG. 2 and the upper 52 and lower films 53 are brought into contact with each other at the depressed position.
FIG. 4 shows a first configuration of a state of the input coordinate sensor in which the touch panel is in the state of FIG. 2. When the user pushes a particular point on the touch panel in the situation of FIG. 4, the sensor conducts control operation to drive switches thereof to enter a subsequent state.
As a result of the control operation of the switches, a linear potential distribution is formed on the first resistor 603 ranging from a voltage V (volt) to 0 (volt) in a direction as indicated by an arrow mark a as shown in FIG. 4.
In FIG. 4, an arrow mark b designates a point (to be referred to as a xe2x80x9ccontact pointxe2x80x9d herebelow) at which the first and second transparent resistive films 601 and 602 come in contact with each other. By reading a value indicated by the A/D converter 609 in this state, an electric potential at the contact point indicated by the arrow mark b on the second resistor 604 can be detected. Since the potential is linearly distributed on the second resistor 604 ranging from a voltage V (volt) to 0 (volt), the obtained potential tells distance of the point from the electrode c in the direction of the arrow mark a. When the direction is aligned to that of an x axis of the coordinate system, the obtained value represents an x coordinate value.
FIG. 5 shows a second construction of a state of the input coordinate sensor associated with the state of the touch panel in FIG. 2. In response to depression at a particular point on the touch panel in the state shown in FIG. 4, the sensor controls its switches to enter a next state.
As shown in FIG. 5, the control operation of the switches causes a linear potential to ve linearly distributed on the first resistor 603 ranging from a voltage V(volt) to 0(volt) in a direction as designate by an arrow mark d.
In FIG. 5, an arrow mark b indicates a point (a contact point) between the first and second transparent resistive films 601 and 602. By sensing a value resultant from the A/D converter 610 in this situation, potential at the contact point indicated by the arrow mark b on the first resistor 603 can be detected. Also distributed on the first resistor 603 is a linear potential ranging from a voltage V (volt) to 0 (volt), the potential represents distance of the point from the electrode e in the direction of the arrow mark d. By aligning the direction to that of a y axis of the coordinate system, the obtained value represents a y coordinate value.
In the prior-art touch pen using transparent resistive films, a pair of x and y coordinates of the point touched or depressed by a pen or a fingertip can be sensed through the operations shown in FIGS. 4 and 5.
FIGS. 6A and 6B show cross-sectional views of an embodiment of a prior-art touch panel of transparent resistive film type. When the dot spacers 55 are arranged with a smaller interval therebetween as shown in FIG. 6A, distance (an area associated with depression on the touch panel) between supporting points (dot spacers) of the distorted films 51 and 52 is reduced. That is, stronger pressure is required to bring the first and second transparent resistive film 52 and 53 into contact with each other. When the dot spacers 55 are disposed with a larger interval therebetween as shown in FIG. 6B, distance (an area corresponding to depression on the touch panel) between supporting points (dot spacers) of the depressed films 51 and 52 is enlarged. This indicates that relatively weaker pressure is necessary for the film 52 to come contact with the second film 52.
As above, in the touch panel using transparent resistive films of the prior art, load necessary to establish the contact state between the upper and lower transparent resistive films is adjusted according to the interval between the dot spacers.
For example, in a touch panel exclusively used with a pen, the dot spacer interval is relatively smaller such that stronger pressure is required to bring the upper and lower films into contact with each other. In operation, even when other than a pen, for example, a part of the user such as a palm touches the touch panel, an erroneous operation does not easily take place. That is, the palm is softer than the pen and hence comes into contact with the touch panel (the transparent film) through a wider area. Load thereof imposed on the touch panel is applied not at one point but at an area in a distributed manner. Therefore, the load is relatively weaker and does not easily bring the upper transparent resistive film into contact with the lower transparent resistive film. Consequently, the touch panel can continue normal operation without errors.
In a touch panel dedicatedly used with fingers, the dot spacer interval is relatively wider. That is, less strong pressure is necessary to bring the upper and lower films into contact with each other. As described above, when compared with a pen input, the finger input is softer and its load is distributed. Therefore, to sense the contact state between the upper and lower transparent resistive films under weaker pressure of a finger, the dot spacers are disposed with a relatively wider interval therebetween.
However, in the touch panels using transparent resistive films shown in the prior art examples, the dot spacers are arranged with an intermediate interval therebetween so that the touch panel is used with a pen and fingers. Therefore, in a pen-input mode, when a part of a hand mistakenly touches the touch panel, an erroneous input easily takes place. Since the dot spacer interval is smaller than that of a touch panel for use with fingers, higher pressure of a finger is required for recognition of the input operation.
It is therefore an object of the present invention to provide a touch panel input device capable of sensing input operation using a pen and a fingertip.
In accordance with the present invention, there is provided a touch panel input device, comprising a first touch panel and a second touch panel, the first touch panel being laminated onto said second touch panel.
In accordance with the present invention, the first touch panel comprises a first transparent film, a second transparent film, a first transparent resistive film arranged on a lower surface of said first transparent film, a second transparent resistive film arranged on an upper surface of said second transparent film, and first dot spacers arranged between said first and second transparent resistive films, said first transparent resistive film opposing said second transparent resistive film. It is preferable that first dot spacers is arranged with an equal interval between the first and second transparent resistive films.
In accordance with the present invention, the second touch panel comprises a third transparent resistive film arranged on a lower surface of said second transparent film, a glass substrate, a fourth transparent resistive film arranged on an upper surface of said glass substrate, and second dot spacers arranged with an equal interval between said third and fourth transparent resistive films, said third transparent resistive film opposing said fourth transparent resistive film.
In accordance with the present invention, the second touch panel comprises a third transparent film, a third transparent resistive film arranged on a lower surface of said third transparent film, a glass substrate, a fourth transparent resistive film arranged on an upper surface of said glass substrate, and second dot spacers arranged with an equal interval between said third and fourth transparent resistive films, said third transparent resistive film opposing said fourth transparent resistive film.
In accordance with the present invention, the first dot spacers are arranged with an interval wider than that of said second dot spacers.
In accordance with the present invention, the device further includes a touch panel controller for controlling said first and second touch panels. The controller includes determining means for determining, according to a contact state between said first and second transparent resistive films of said first touch panel and a contact state between said third and fourth transparent resistive films of said second touch panel, that an input operation is conducted by a fingertip or a pen.
In accordance with the present invention, the determining means determines, when said first and second transparent resistive films is in a contact state and said third and fourth transparent resistive films is in a non-contact state, that the input operation is conducted by a fingertip. The determining means determines, when said first and second transparent resistive films is in a contact state and said third and fourth transparent resistive films is in a contact state, that the input operation is conducted by a pen.
In accordance with the present invention, there is provided a touch panel input device which has structure including two touch panels attached onto each other to thereby enhance good usability as a touch panel for a finger and as a touch panel for a pen.